In tape cartridge back-up systems for personal computers, parallel tracks of data are recorded on a tape medium in a data cartridge. Generally, a tape cartridge is inserted into a drive mechanism which has a magnetic head that contacts the magnetic tape within the cartridge through an opening in the front of the cartridge. The magnetic head with one or more read/write gaps must be positioned on the tracks such that the magnetic head gap(s) centerline is within a prescribed dimensional tolerance of the recorded track centerline. If the magnetic head is properly aligned relative to the position of the tape, the information will be properly recorded. This concept can be visualized with reference to FIG. 1 which shows a strip of magnetic tape 10 with tracks 30 containing individual bits 20. For example, a dark bit represents a 1 and a blank bit represents a 0. FIG. 1 shows a tape with perfect alignment, such that all bits are written within the specifically intended bit and track spacing.
FIG. 2 shows a similar strip of magnetic tape which was recorded with the azimuth of the magnetic head skewed a few minutes of arc-angle relative to the tape. If a tape is recorded and read exclusively in the same tape drive, the situation of FIG. 2 does not pose too much of a problem. However, the current trend is for portability of information from one system to another. Thus, a tape may typically be written by one tape drive and read by another tape drive, which can pose problems if either or both of the magnetic heads of the tape drives are not properly aligned with the tape.
For example, if the write magnetic head is skewed a few minutes to the right and the read magnetic head is skewed a few minutes to the left, then the information will not be readable. Accordingly, consistent magnetic head to tape alignment is a serious issue with regards to reading a tape in one drive that was recorded in a different drive. This requires precision in the alignment, positioning and tracking of the magnetic head.
Most of these alignment problems are addressed by industry standard tape and tape cartridge physical dimensions and prescribed dimensional tolerances for the alignment of the magnetic head within the tape drive relative to the positioning of the tape cartridge within the tape drive during use. However, currently tape backup devices are being mounted and used in computer bays of various different computer manufacturers. This raises a new alignment issue. Specifically, when a tape drive is mounted into a computer bay, the mounting holes of is the computer bay may not be co-planar or the computer bay itself may be twisted, which may cause the tape drive chassis to be torsionally twisted within the computer bay. If a tape drive is torsionally twisted in the computer bay, the azimuth of the magnetic head to tape alignment may be outside of the industry standard of .+-.10', which could result in poor read/write performance and make interchangeability between different tape drives difficult. This torsional twisting of a tape drive could also cause binding of internal mechanisms in the tape drive, resulting in excess wear, poor read/write performance, poor cartridge detection, poor beginning and end of tape hole sense, and other system failures.
Many tape drive manufacturers address this problem by adding additional parts to the outside of the drive chassis to isolate the chassis from the computer bay. This solution adds additional cost and complexity to the tape drive design, the cost and number of parts, and the cost and complexity of assembly and disassembly. Accordingly, there is a need in the field of magnetic tape drives for an inexpensive, simple means of maintaining proper feature alignment within the tape drive chassis when the drive is installed in a twisted computer bay or in a computer bay with mounting holes that are not co-planar. There is a further need for a means of maintaining proper feature alignment within the tape drive chassis that does not add additional parts, weight, or assembly/disassembly complexity or cost.